Squeezing a slice of lime into a refreshing drink on a hot summer day isn’t as harmless as you may think. Fredrikke and Selma, two young Norwegian girls, found that out first hand after they suffered from severe Margarita Dermatitis during their vacation in Spain.

Fredrikke and Selma, both seven years old, were vacationing with their families in the Spanish resort of Marbella. One day, during an outdoor lunch, they spotted a lime tree and thought it would be fun to squeeze juice out of its fruits. They went at it for about an hour, enthusiastically squeezing dozens of limes, before going to the beach for a swim, one of the girls’ parents told Norwegian website, Klikk. But when Fredrikke woke up the next morning, both her hands were swollen and the skin felt tender to the touch. Thinking it might be a reaction to mosquito bites, her mother, Kathryn, gave the girl an allergy pill. Only when they met up with Selma’s family and noticed she presented the exact same symptoms, it became clear that what ever was affecting them had something to do with the limes they had squeezed the other day. After a few hours, both Fredrikke and Selma started complaining of burning pain and their hands began to blister. On the morning of the third day, Fredrikke’s hands looked even worse and her parents knew they had to seek medical help as soon as possible. They jumped on the first plane home, gave the girl painkillers so she could sleep during the flight, and rushed her to the emergency room as soon as they landed in Oslo. Selma and her family had another week of vacation left so they went to the hospital in Marbella.

Initially, neither the doctors in the emergency room nor those at Marbella Hospital could place a diagnosis on the two girls, but since the symptoms resembled burns, they treated them accordingly. They applied vaseline compresses on the girls’ hands and wrapped them in bandages to keep the moisture in. Fredrikke and Selma were also given penicillin to prevent infection and blood poisoning, and after two weeks their condition started to improve. Now, almost a month since they squeezed those limes, their hands are still covered with dark dead skin that has to be cut off gradually. They no longer feel any pain, though, and doctors say that due to their young age, the girls are going to make a full recovery. For the moment, Fredrikke and Selma are required to wear mittens to protect their hands until they heal completely, and will have to wear sunscreen with a SPF rating of 50 until next summer, to protect the new sensitive skin.

Hartmut Heisterkamp, the head of the burn unit at Haukeland University Hospital, says Fredrikke and Selma suffered from a severe case of phytophotodermatitis. The condition was first described in 1942 as a reaction between certain plants and sunlight. Its symptoms are very similar to burn injuries and they are actually treated the same way. During the summer months, lime juice is the common cause for this condition, which is why many doctors call it “Margarita Dermatitis“, but it can also be caused by lemons, parsley, celery, carrot and figs. Most cases resemble a mild sunburn or poison ivy rash, but in extreme cases, like the one detailed above, it can cause severe damage to the skin if left untreated.

So the next time you feel the need for a refreshing lemonade or lime cocktail, make sure to squeeze the fruit out of direct sunlight, or at least wear some kind of protection for your skin.